Atrial fibrillation (AF), a common type of heart arrhythmia, is a major risk factor for stroke. About 15 percent of all strokes are attributable to atrial fibrillation. Anticoagulants such as Warfarin, as well as beta blockers and calcium channel blockers, may be prescribed to reduce the risk of stroke.

How common is atrial fibrillation? Data from the Framingham Heart Study, which followed over 8,000 Massachusetts residents from 1966-1999, indicate that the average lifetime risk after age 40 was 26% for men and 23% for women, and that the risk remained relatively constant as individuals grew older. [PMID 15313941]